Hydraulic tree pruner



March 29, 1960 a. M. PFUNDT nyomuuc TREE PRUNER Filed, June 27. 1957 INVENTOR, GEORGE M. PFu/vm fiTTORNEY HYDRAULIC TREE PRUNER George M. Pfundt, Churchville, Pa. Application June 27, 1957, Serial No. 668,372

6 Claims. (CL 30-228) This invention deals with what are known as pruning tools and, particularly, tools of this type and kind employing a pair of jaws at the outer or upper end of a long shaft or pole. More particularly, the invention deals with a tool of the character described, wherein the jaws are hydraulically operated in cutting branches from Fig. 1 is a side and sectional view through a tool' made according to my invention, with parts of theconstruction broken away and illustrating the jaws of the tool in open position,

.Fig. 2 is an enlarged section 2--2 of Fig. 1. 1

Fig. 3 is an enlarged section on theline 3-3 of Fig. 1, omitting most of the background showing; and

Fig. 4 is an enlarged section on the line 44 of Fig. l.

In carrying my invention into effect, I provide, as noted in Fig. l of the drawing, an upper pole or tube 10, to the lower end of which is secured a larger diameter and preferably heavier walled pole or tube 11. The poles 10 and 11 can be composed of aluminum for lightness of the pole. Attached to the lower end of the pole 11 is a steel cylinder 12,

Fixed to the upper end of the pole 10 is apivot-cap 13, having a reduced forked upper end 14, in which is mounted a pivot bolt 15, the head 16 and nut 17 of which preferably have conical outer surfaces, which are within the boundaries of the cap 13, as noted in Fig. 2 of the drawing. The bevelled outer surfaces referred to eliminate the possibilities of hook engagement of the tool with branches in the use of the tool.

Pivotally mounted on the pivot bolt 15 are a pair of cutter jaws 18 and 19, having opposed bevelled cutter edges, as indicated at 20 in Fig. l of the drawing. Outer extremities of the cutter ends of the jaws have opposed bevels, as at 21, so as to prevent the tip ends of the jaws from striking each other in a cutting operation and Jinsuring completion of the jaw stroke in cutting a branch or limb.

The jaws 18 and 19 have downwardly extending arm portions 22 and 23, with which are pivoted operating links 24 and 25, respectively.

The lower ends of the links 24, 25 have apertures which are brought into alinement and pivotally engaged by a pivot pin 26, note Fig. 3 of the drawing, the pin being housed within the upper pole 10 and mounted in a forked block 27 slidably mounted in the upper pole 10-.

It will appear that the pole 10 has, at opposed sides, offset elongated slots 28 and 29, in which the links'24, 25, respectively, operate in movement of the jaws into closed and open positions. The block 27 has a reduced threaded stud 30 fixed to the upper end of an inner tube substantially on the line 31 vslidably and freely mounted in the pole 10.

Mounted in the lower pole 11 and guided in an Oil lite bearing 32 is a piston rod 33, the upper end of which has a threaded stud 34 fixed to the lower end of the inner tube 31. Mounted on a lower reduced end 35 of the rod 33 is 'a piston 36 operating in the cylin-' der 12 and having suitable sealing ring portions, diagrammatically illustrated at 37. The piston is sealed upon the reduced portion 35 by an O-ring seal 38.

The lower end of the cylinder 12 is closed by an inwardly set bottom wall 39, in which are mounted two small and large diameter pipes 40, 41, respectively, which open into a bypass chamber 42 maintained at all times below the lower end of the piston 36. The piston is shown in its lowermost position in Fig. 1 ofthe draw"- ing. The-pipe 40 comprises the pressure tube for the pressure feed of oil into the chamber 42 in hydraulically moving the piston 36 upwardly to, in turn, move the jaws 18 and 19'into closed or operativeposition.

The larger diameter pipe 41 is coupled with a control valve 43 diagrammatically detailed in Fig. 4 of the drawing. The valve 43 has a casing 44, in the bore 45 of which is mounted a control plunger 46 having a short sealing end 47 and a long-operating end 48, both snugly operating in the bore 45 and sealed by O-rings, as at I 49. It will be noted that the pipe 41 is disposed near what can be termed the inner end of the valve 43 andanother pipe 50 is coupled with the valve 43 and com-, municates with'the bore near the forward end of the valve. Normally, the plunger 46 assumes the position'showlr in Fig. 4 and is retained in this position by a snap ring 51 mounted on the end 47 of the plunger and, by action of a coil spring, diagrammatically shown at 52, the spring seating on a collar 53 supported on the forward end' of the plunger 46 by a screw 54. In this normal posi-"' tion of the valve 43, the hydraulic medium passes through the chamber 42 through the bore 45 between" the ends 46 and 47 and returns to the tank of the hy draulic system through the-pipe 50. It will be apparent,v

however, that, upon pushing the plunger 46 inwardly to seal such discharge through the pipe 50, the pressure will be maintained and, thus, the hydraulic medium will act upon and force the piston 36 upwardly in the oper-l ation of the jaws 18 and 19. An elongated coil spring,-

diagrammatically illustrated in part at 55, is disposed be; tween the piston 36 and the bearing portion, as at 32,: and serves to return the piston to its lowered position;

shown in Fig. 1, upon return of the valve 43, to the inoperative position of Fig. 4. The complete showing of the spring 55 has been omitted solely fo'rthe purpose of:

simplifying the showing.

Considering Fig. 1 of the drawing, it will appearthat a supporting hook 56 is welded or otherwise secured tothe upper end portion of the cylinder 12m facilitate sup* port of the tool upon a belt socket or belt of an operator, so that a great portion of the weight of the tool can-be supported about thewaist, thus providing of the 'cylinder 12' a lower handgrip end in adjustment of the tool for engagement with a branch or limb to be cut. In this con-' nection, it will be apparent that the supporting hook 56; 1

poles of the tool forms a fulcrum, about which the can be swung.

Having fully described as new and desire to secure by Letters Patent is:

1. A pruning tool, comprising upper and lower small and large diameter tubular poles, a pair of pruning'jawsf pivotally mounted in connection with" the-upper pole; said jaws having arm portions substantially-in longitudinal alinement with said jaws, the major portion of the inner cutting edges of which are parallel with each other and with the poles when the jaws are in open position, a hydraulio cylinder mounted in connection with the lower Patented Mar. 29,

my invention, what I claim.

pole, a piston operating in said cylinder, the piston having a rod operating in both of said poles, a tube directly coupled with said rod and freely disposed in the upper pole, a pair of links pivotally coupled with the upper end of said tube and pivotally coupledwith the arms of said jaws for actuation of the jaws by upward movement of said rod and lateral spread of said arm portions in introduction of a hydraulic medium into said cylinder, and a control valve supported on the cylinder controlling operation of said hydraulic medium.

2. A pruning tool, comprising upper and lower small and large diameter tubular poles, a pair of pruning jaws pivotally mounted in connection with the upper pole, said jaw having arm portions substantially in lonigtudinal alinement with said jaws, the major portion of the inner cutting edges of which are parallel with each other and with the poles when the jaws are in open position, a hydraulic cylinder mounted in connection with the lower pole, a piston operating in said cylinder, the piston having a rod operating in both of said poles, a tube directly coupled with said rod and freely disposed in the upper pole, a pair of links pivotally coupled with the upper end of said tube and pivotally coupled with the arms of said jaws for actuation of the jaws by upward movement of said rod and lateral spread of said arm portions in introduction of a hydraulic medium into said cylinder, a control valve supported on the cylinder controlling operation of said hydraulic medium, the upper end of said pole including opposed otfset elongated slots, in which said link are guided and operate, and the lower pole having, adjacent its coupling with the upper pole, a long bearing portion for guide of the piston rod in operation thereof.

3. A pruning tool, comprising upper and lower small and large diameter tubular poles, a pair of pruning jaws pivotally mounted in connection with the upper pole, said jaws having arm portions substantially in longitudinal alinement with said jaws, the major portion of the inner cutting edges of which are parallel with each other and with the poles when the jaws are in open position, a hydraulic cylinder mounted in connection with the lower pole, a piston operating in said cylinder, the piston having a rod operating in both of said poles, a tube directly coupled with said rod and freely disposed in the upper pole, a pair of links pivotally coupled with the upper end of said tube and pivotally coupled with the arms of said jaws for actuation of the jaws by upward movement of said rod and lateral .spread of said arm portions in introduction of a hydraulic medium into said cylinder, a control valve supported on the cylinder controlling opcration of said hydraulic medium, the upper end of said pole including opposed offset elongated slots, in which said links are guided and operate, the lower pole having, adjacent its coupling with the upper pole, a long bearing portion for guide of the piston rod in operation thereof, and the pivotal coupling of the links with said tube comprising a forked block coupled with said tube and snugly fitted in and slidable in the upper Pole.

4. A pruning tool, comprising upper and lower small and large diameter tubular poles, a pair of pruning jaws pivotally mounted in connection with the upper pole, said jaws having arm portions substantially in longitudinal alinement with said jaws, the major portion of the inner cutting edges of which are parallel with each other and with the poles when the jaws are in open position, a hydraulic cylinder mounted in connection with the lower pole, a piston operating in said cylinder, the piston having a rod operating in both of said poles, a tube directly coupled with said rod and freely disposed in the upper pole, a pair of links pivotally coupled with the upper end of said tube and pivotally coupled with the arms of said jaws for actuation of the jaws by upward movement of said rod and lateral spread of said arm portions in introduction of a hydraulic medium into said cylinder, a control valve supported on the cylinder controlling operation of said hydraulic medium, and the pivotal mounting of the jaw with the upper end of the upper pole comprising a cap threaded on and projecting beyond the upper pole and having a reduced forked end supporting a pivot bolt, on which said jaws are rotatably mounted.

5. A pruning tool, comprising upper and lower small and large diameter tubular poles, a pair of pruning jaws pivotally mounted in connection with the upper pole, said jaws having arm portions, the major portion of the inner cutting edges of which are parallel with each other and with the poles when the jaws are in open position, a hydraulic cylinder mounted in connection with the lower pole, a piston operating in said cylinder, the piston having a rod operating in both of said poles, a tube directly coupled with said rod and freely disposed in the upper pole, a pair of links pivotally coupled with the upper end of said tube and pivotally coupled with the arms of said jaws for actuation of the jaws in introduction of a hydraulic medium into said cylinder, a control valve supported on the cylinder controlling operation of said hydraulic medium, the pivotal mounting of the jaws with the upper end of the upper pole comprising a cap secured to and projecting beyond the upper pole and having a reduced forked end supporting a pivot bolt, on which said jaws are rotatably mounted, the head of said bolt and the bolt nut having conical outer surfaces disposed within the environment of the cap diameter, and a spring mounted in the lower pole and said cylinder for return of the piston to inoperative position in said cylinder.

6. A pruning tool, comprising upper and lower small and large diameter tubular poles, a pair of pruning jaws pivotally mounted in connection with the upper pole, said jaws having arm portions, the major portion of the inner cutting edges of which are parallel with each other and with the poles when the jaws are in open position, a hydraulic cylinder mounted in connection with the lower pole, a piston operating in said cylinder, the piston having a rod operating in both of said poles, a tube directly coupled with said rod and freely disposed in the upper pole, a pair of links pivotally coupled with the upper end of said tube and pivotally coupled with the arms of said jaws for actuation of the jaws in introduction of a hydraulic medium into said cylinder, a control valve supported on the cylinder controlling operation of said hydraulic medium, and outer extremities of the jaws having oppositely bevelled tips for guidance of the tips one over the other in movement of the jaws into operative position.

References Cited in the file of this patent UNITED STATES PATENTS 596,890 Le Sage Jan. 4, 1898 639,525 Conatser Dec. 19, 1899 728,068 Young May 12, 1903 944,555 Holden Dec. 28, 1909 2,070,225 Dickson Feb. 9, 1937 2,075,341 Goodman Mar. 30, 1937 2,242,476 Newman May 20, 1941 2,249,515 Carroll July 15, 1941 2,366,909 Johnson Jan. 9, 1945 2,446,011 Johnson et 'al. July 27, 1948 2,488,224 Mothorn Nov. 15, 1949 2,543,109 Holowka Feb. 27, 1951 2,548,175 Schellinger Apr. 11, 1951 2,699,756 Miller Jan. 18, 1955 

